The quest to produce quality and technically-effective three-dimensional images has continued for a number of years. Basically, there are two types of presentation methods or systems that are available for viewing three-dimensional images; these are broadly characterized as either stereoscopic or autostereoscopic.
In stereoscopic systems, pairs of ordinary two-dimensional still photographs or binocular motion pictures are made of an object from two points of view. The two points are separated by a distance equal to the distance between the eyes of a viewer. The pair of photographs or motion pictures are then viewed by a device that allows the right eye to see only the right image and the left eye only the left image. In this viewing system, each eye sees a slightly different image; thereby duplicating the conditions under which the original scene would have been viewed. Consequently, the viewer is aware of only one image that has a three-dimensional effect.
To view objects stereoscopically, the stereo photographs or moving pictures must be separated by an opaque area that allows the right eye to see only the right view and the left eye only the left view. several systems have been devised to permit stereoscopic viewing. For example, red and green tinted monochrome images are both displayed to be viewed by glasses having left and right lenses with corresponding red and green tints; or two color images are projected through mutually perpendicular polarized filters and are then viewed through glasses that are polarized in the same manner.
In autostereoscopic systems, it is not necessary for the viewer to wear special glasses or to use any other viewing implement to keep the two images separated. What the viewer sees is not the pair of two dimensional images as described above, but rather a set of images that either appear to be distributed over three dimensions or are actually distributed over three dimensions. A holographic image is an example of the first type of autostereoscopic imaging. The second type of autosteroescopic imaging is currently achieved by the use of moving screens or vibrating varifocal mirrors that are vibrated by an oscillating frequency that causes the mirror to have a continuously variable focal length. In both types, the image is constantly moved back and forth in the image space provided. This movement causes the images to fuse together and because of the persistence of the eyes a three-dimensional image is perceived.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention however, the following U.S. patents were considered related:
______________________________________ U.S. PAT. NO. INVENTOR ISSUED ______________________________________ 4,747,665 O'Brien 31 May 1988 4,714,319 Zeevi et al 22 December 1987 4,571,041 Gaudyn 18 February 1986 3,248,165 Mark et al 26 April 1966 ______________________________________
The O'Brien patent discloses a method for displaying three-dimensional images. The method consists of driving a flexible membrane mirror by a composite waveform that consists of triangle and sinusoidal waves. The composite waveform displaces the flexible membrane mirror so that the mirror's surface is alternatively convex and concave. The driving waveforms are then synchronized to display an alternating sequence of two-dimensional images on a CRT screen such that the viewer perceives a three-dimensional image.
The Zeevi et al patent discloses a method of generating disparate information for imparting depth perception to an image. The depth perception is created by projecting an image of an object using a plurality of energy sources to create a plurality of images having different shadows. A single detector, such as a camera, detects and successively records the object with the object illuminated for successive frames from light sources at spaced apart locations. When viewed, the image will have a three-dimensional effect that in substance, is a shadowgram having an illusion of depth.
The Gaudyn patent discloses a three-dimensional projection arrangement for projecting dual three-dimensional images of objects into space for viewing by an unaided audience. The objects are illuminated by a source of light, and the light rays reflected from the objects are directed so as to be incident on a mirror surface located behind a lens and the combination forms the enlarged three-dimensional images that are projected into space. The lens can be in the form of a modified fresnel lens that provides a substantially large field of view.
The Marks et al patent discloses a moving screen projection system that simulates a three-dimensional presentation. The system includes plural projectors that are combined with at least two viewing screen spaced from each other. The multiple screen system includes (1) a foreground reflecting surface having holes for passing some of the projected light, (2) a polarizing film on the screen which passes only light polarized in a first plane, and (3) a diffusing layer that diffuses the reflections of the incident light. A background screen is mounted behind the foreground screen for receiving and reflecting light passed through the holes.